This invention relates to offshore mooring and loading terminals and more particularily to a method and means for indicating to a ship that the load on the mooring facility on the buoy may be reaching or has reached a level at which it is advisable that the ship should cast off in order to avoid serious damage to the mooring equipment.
Offshore loading and unloading facilities such as single buoy offshore terminals are available for transferring fluid cargoes and supplies between ships, particularly large tankers and other sea-going vessels, to onshore storage facilities. These offshore terminals are becoming more and more numerous as the draft required for ships, particularly large tankers, becomes greater than the depth of many of the harbors on which these ships call. Also, these offshore loading terminals provide a large measure of safety since, ships with dangerous cargoes are permitted by means of these offshore loading terminals, to anchor sufficiently far enough offshore so that they will not constitute a danger or menace to a harbor.
One of the recent, more popular, offshore loading terminals is the kind that has a swivel assembly that permits ships that are moored thereto to swivel or weathervane freely about the buoy in response to changes of tide and weather during transfer operations. However, whether or not the buoy is of the type which permits the ship to weathervane, one of the problems that can arise is that while a ship is moored to one of these buoys, the weather or tide, in certain areas, such as the North Sea, can change to such an extent that it is unsafe for the ship to remain moored to that buoy. This occurs because of the fact that the stresses which are created on the mooring equipment are such that it will give way, damaging the mooring equipment and possibly rupturing the hoses which extend between the ship and the buoy for the purpose of transferring fluid cargo there between. Therefore, it becomes desirable to determine when it is necessary for a ship to cast loose from a buoy in order to avoid these disasterous consequences. Obviously, it is not desirable to have the ship cast off too soon, since that requires termination of the loading or unloading process, and the ship would have to stand by until it was safe to again moor to the offshore floating terminal. This constitutes time during which a ship is not being used as a result of which there is a substantial loss to the owners.